1. Field of the Invention
The present invention relates to the use of an astaxanthin pigment product obtained by semi-synthesis from marigold extract to substantially enhance the feeding and growth rates of commercially farmed species such as trout, salmon and shrimp when added to the meal in concentrations useful in producing animal coloration. More particularly, this product induces growth rates substantially greater than any currently available food additive for aquaculture. Growth rates are especially enhanced for salmonid species such as salmon and trout and for shrimp. The economic impact of the ability to harvest fish and other animals such as shrimp much earlier is very meaningful in commercial aquaculture.
2. Description of the Related Art
Aquaculture is an increasingly important area of commerce around the world. Certain aquatic species derive flesh color from natural feeding sources. Such species as salmon, trout, koi, tropical fish, abalone, sea bream and crustaceans such as shrimp and lobster are the most common species which derive this natural pink color, astaxanthin, from the environment. However, when such species are commercially farmed, they no longer have access to this colorant and it is necessary to add it to the feed. It is known that addition of this material to the fish feed enhances the health and lowers the stress on the fish while also providing the necessary coloring of the flesh (Torrissen, O. J and Cristiansen, R., J. Appl. Ichthyol, 11, 225 (1995). Until recently, the only commercial sources of astaxanthin product were derived from total synthesis or the fermentation of Pfaffia rhodozyma yeast or growing of Haematococcus alga.
Recently, Breivik et al. (WO 03/003848) reported that the growth of Atlantic salmon was enhanced when the fish were fed an astaxanthin diester in combination with a concentrate comprising two different omega-3 fatty acids, compared to fish fed commercially available synthetic astaxanthin (Carophyll Pink, Roche). It should be noted that the maximum increase in growth after 15.5 months was only 9% above control. The inventors suggest that the diester form provides better growth rates in salmonid species than free unesterified astaxanthin.